Stall - Review of the Fundamentals, the Procedure and the ... · Airbus Flight Instructor Seminar...

Airbus Flight Instructor Seminar Miami

StallReview of the Fundamentals, the Procedure and the Training

May 2011

Presented byCapt. Christian Norden/ Flight Crew Development

© AIRBUS S.A.S. All rights reserved. Confidential and proprietary document.


Content

• Introduction

• Stall phenomenon

• Angle of Attack Control and Stall Recovery

• Stall v/s Approach to Stall

• New Procedures

• Airbus Training Proposal (Operator Training Telex)

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INTRODUCTION

• Accidents following failure to recover from stall

still occur

• It is also an issue for the transport aircraft environment

• Objective of this presentation:

“Make the operational community aware of the review of the

traditional methods of STALL and APPROACH TO STALL

recovery techniques.”

3



INTRODUCTION

• Stalls are frequently performed in flight test by all aircraft

manufacturers for development and certification

• Unique experience to be shared with operational community

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Content

• Introduction




• New Procedures


5



AERODYNAMIC REVIEW

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LIFT COEFFICIENT

For a given configuration, a given speed and a given altitude,

Lift is only linked to Angle of Attack

• Cl has a direct relationship to AoA

Cl

AoA

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STALL

• At a given AoA, the air flow separates from the profile, the Cl drops

For a given aircraft configuration and speedAn aircraft stalls for a given Angle off Attack

The wing profile is stalled

• Cl has a direct relationship to AoA

1

3

2

1

2

3

Cl

AoA

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Key message:

May 2011

Stall is an Angle of Attack (AoA) problem only

- it is NOT directly a speed issue



STALL DEMONSTRATION

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Content

• Introduction




• New Procedures


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AoA CONTROL - out of normal law

CG

Pitch control is a direct AoA commandThe elevators control DIRECTLY the AoA.

A nose down command has an IMMEDIATE effect : an AoA decrease

AoA

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The pitch control is a direct AoA command• The elevators control DIRECTLY the AoA.

• A nose down command has an IMMEDIATE effect : an AoA decrease

AoA

CG

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AoA

CG

• Aircraft with engine below aircraft CG ⇒Thrust has a significant pitch effect

Thrust increase

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AoA

CG


Thrust increase ⇒ AoA increase

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AoA

CG


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AoA

CG


Thrust reduction

Thrust reduction ⇒ AoA decrease

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STALL RECOVERY When Aircraft is stalled

• FIRST: AoA MUST BE REDUCED• Release back pressure on stick or column

• Nose down pitch input may be needed

Note : Thrust has an adverse effect on AoA for Aircraft with engines below aircraft CG

• SECOND: When out of the stall, increase speed if needed• Smoothly increase thrust, with care due to thrust pitch effect

AoA comes first, speed second

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Content

• Introduction




• New Procedures


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STALL v/s APPROACH TO STALL

• Traditional APPROACH TO STALL TRAINING is characterized by controlled deceleration to stall warning, followed by a power recovery with minimum altitude loss.

• Difference between an APPROACHING STALL and an actual STALL is not easy to determine, even for specialists!

• Numerous accidents where the APPROACH TO STALL procedure was applied whereas the aircraft was actually STALLED.

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STALL v/s APPROACH TO STALL

• Traditional APPROACH TO STALL PROCEDURE focused on:• thrust application • minimum loss of altitude

• NOT appropriate for recovery from ACTUAL STALL condition:• Possible inability to reduce AoA with the high thrust application• Recovery may even require thrust reduction• Recovery from a stall may require altitude loss

A new SINGLE PROCEDURE had to be defined

focusing on AoA reduction (covering Approach to Stall and Actual Stall)

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Content

• Introduction




• New Procedures


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Rationale for the new procedure:

• One single procedure to cover

Approach to Stall and Actual Stall

• Focus on AoA reduction

• Remove TOGA as first action

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The new procedure



Spurious Stall Warning at Lift Off



Content

• Introduction




• New Procedures


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Proposed Training

• Thorough briefing before the session, reviewing the stall fundamentals, the QRH procedures e.g.

• FCOM emergency procedures / stall recovery• QRH stall recovery • FCTM abnormal operations / operating techniques / stall recovery • Power point presentation on Airbus World portal• Safety First magazine, issue 11, edition January 2011

• Stall recovery exercises during a visual circuit as described in the following slides (may be integrated in the Recurrent Training as convenient)

Remark: MFF pilots need to make the training on one type only

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Proposed Scenario for Training:

May 2011

• Select a weight equivalent to the maximum landing weight

• Select CAVOK conditions

• Perform a standard visual pattern

Caution !Training shall be conducted only afterreceiving full information by Airbus -Operator Training Telex, TrainingRecommendation - Recovery from Stall .



Scenario for Training:

May 2011

• Configure the aircraft according SOP





May 2011

• Turning on base leg, ask the trainee to reduce thrust to idle and to maintain the present altitude

• Introduce Alternate Law





May 2011

• When the trainee observes a stall warning or any other stall indication/clues (aural warning, buffet…):

• the actions according FCOM and QRH must be applied immediately.

• After the stall recovery, stop the exercise

• Reposition on downwind, repeat the exercise until trainee feels confident and is proficient.

• Training time required about 15 minutes/trainee Caution !Training shall be conducted only afterreceiving full information by Airbus -Operator Training Telex, TrainingRecommendation - Recovery from Stall .



Operations Training Telex

May 2011

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• This new training proposal will be published soon via OTT (Operations Training Telex) containing more details on the conduct of the exercise

• OTT is a new tool by Airbus to communicate with you regarding significant training issues.

• OTT-Stall Training will be published within the next few weeks.

• Your feedback is highly welcome!



© AIRBUS S.A.S. All rights reserved. Confidential andproprietary document.

This document and all information contained herein is the soleproperty of AIRBUS S.A.S.. No intellectual property rights aregranted by the delivery of this document or the disclosure ofits content. This document shall not be reproduced ordisclosed to a third party without the express written consentof AIRBUS S.A.S. This document and its content shall not beused for any purpose other than that for which it is supplied.

The statements made herein do not constitute an offer. Theyare based on the mentioned assumptions and are expressedin good faith. Where the supporting grounds for thesestatements are not shown, AIRBUS S.A.S. will be pleased toexplain the basis thereof.

AIRBUS, its logo, A300, A310, A318, A319, A320, A321,A330, A340, A350, A380, A400M are registered trademarks.

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